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Your QuestionWe have a 2-year-old son who was diagnosed with Angelman syndrome. He has a deletion of the mother's part on chromosome 15. What are the chances of this syndrome occurring in our next baby? We have another 6-year-old son who is normal.
We have identified the following information that we hope you find helpful. If you still have questions, please contact us.
Questions on this page
- What is Angelman syndrome?
- What causes Angelman syndrome?
- How might Angelman syndrome be inherited?
- After having one child with Angelman syndrome, what is the chance that future children will inherit it as well?
- Is there any way to avoid having a child with Angelman syndrome in a future pregnancy?
- How can I find a genetics professional in my area?
Several different genetic mechanisms can inactivate or delete the maternal copy of the UBE3A gene. Most cases of Angelman syndrome occur when a segment of the maternal chromosome 15 containing this gene is deleted. In other cases, Angelman syndrome is caused by a mutation in the maternal copy of the UBE3A gene.
In a small percentage of cases, a person with Angelman syndrome inherits two copies of chromosome 15 from his or her father, instead of one copy from each parent. This is called paternal uniparental disomy. Rarely, Angelman syndrome can also be caused by a chromosomal rearrangement called a translocation, or by a mutation or other defect in the region of DNA that controls activation of the UBE3A gene. These genetic changes can abnormally turn off (inactivate) UBE3A or other genes on the maternal copy of chromosome 15.The cause of Angelman syndrome is unknown in 10 to 15 percent of affected individuals. Changes involving other genes or chromosomes may be responsible for the condition in these individuals.
Rarely, a genetic change responsible for Angelman syndrome can be inherited. For example, it is possible for a mutation in the UBE3A gene or in the nearby region of DNA that controls gene activation to be passed from one generation to the next.
Prenatal diagnosis can be used to diagnose a condition in a developing fetus. If the underlying genetic cause of a disorder in a family is known, testing can be completed to analyze the genetic material of the fetus. This is typically completed around 10-13 weeks' gestation via chorionic villus sampling or around 15+ weeks' gestation via amniocentesis. Prenatal diagnosis may help parents prepare emotionally for the birth and to plan the delivery with their health care providers. Parents can also use this information to make decisions regarding whether or not to continue the pregnancy.
PGD is an alternative to prenatal diagnosis. It is used following in vitro fertilization to diagnose a genetic disease or condition in embryos. Only embryos that do not carry the disease-causing mutation are implanted in the mother's womb. PGD allows testing to occur before a pregnancy begins. In many cases, the disease-causing mutation must be identified in an affected parent before PGD or prenatal diagnosis can be performed.
Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.
The following online resources can help you find a genetics professional in your community:
- GeneTests has a searchable directory of US and international genetics and prenatal diagnosis clinics.
- The National Society of Genetic Counselors provides a searchable directory of US and international genetic counseling services.
- The American College of Medical Genetics has a searchable database of US genetics clinics.
- The University of Kansas Medical Center provides a list of US and international genetic centers, clinics, and departments.
- The American Society of Human Genetics maintains a database of its members, which includes individuals who live outside of the United States. Visit the link to obtain a list of the geneticists in your country, some of whom may be researchers that do not provide medical care.
- Angelman syndrome. Genetics Home Reference. May 2015; http://ghr.nlm.nih.gov/condition=angelmansyndrome.
- Dagli AI, Mueller J, Williams CA. Angelman Syndrome. GeneReviews. May 14, 2015; http://www.ncbi.nlm.nih.gov/books/NBK1144/.
- What are the types of genetic tests?. Genetics Home Reference. June 2011; http://ghr.nlm.nih.gov/handbook/testing/uses.